The present invention relates to an improved pickup arm for phonogrph record players.
In general, a pickup arm device consists of an arm pivotably supported on a bearing, a pickup cartridge supported at one end of the arm for tracing the grooves of a disk and converting mechanical vibrations into electrical signals, and a balance weight supported at the other end of the arm for balancing it. The pickup arm device of the type described exhibits a sharp peak at a resonance frequency of the pickup arm or so-called arm-resonance frequency at low frequencies of a frequency characteristic curve so that a vertical motion with a greater amplitude of the cartridge caused by a bent disk results, exerting undesired excessive forces on a reproducer stylus. As a consequence, intermodulation distortion occurs and in the worst case stylus skating occurs.
So far various pickup arm devices have been devised and demonstrated for suppressing the arm resonance. In one device, an arm and a balance weight are coupled to each other through a resilient coupler such as a rubber member or spring. This device exhibits two resonance peaks or shoulders adjacent to the arm resonance frequency, and they are lowered due to a valley or dip of antiresonance between them. With this device, however, the replacement of a cartridge results the displacement of the two resonance peaks so that they cannot be sufficiently lowered and consequently the above-mentioned problems result.